JPH0229828Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a self-excited converter using a blocking oscillation circuit. More specifically, the main switching transistor is driven by the transformer of the blocking oscillation circuit, thereby achieving a significant power increase. The present invention relates to a self-excited converter that is capable of

There are various types of self-excited converters depending on the configuration of the inverter section, but one of the most widely used is a self-excited converter using a blocking oscillation circuit. As shown in FIG. 1, this system incorporates a blocking oscillation circuit 1 into the inverter section of a self-excited converter, rectifies and smoothes its output with a rectifier circuit 2, and extracts a DC output. That is, as is well known, the blocking oscillation circuit 1 is a positive feedback oscillation circuit having a transistor Q1 and a transformer T1.
repeats the switching operation. In this embodiment, when transistor Q1 is conductive, transformer T1
This is a so-called ON-OFF control in which magnetic energy is stored in the transistor Q1 and released to the load side when the transistor Q1 is turned off. Incidentally, a constant voltage control section 3 is usually incorporated in such a converter, thereby stabilizing the output voltage.

Now, in such a conventionally known self-excited converter, the capacity of the transformer T1 is increased,
Alternatively, even if a large-capacity transistor Q1 is used, the output power that can be taken out is limited to a relatively small amount (usually about 30 W at most). In addition, as another example of a transformer control method,
There is also an ON-ON control type, but it requires a transformer reset circuit, or a rectifier and smoothing circuit that requires additional diodes and choke coils, making the circuit a little complicated. In other words, self-excited converters using such blocking oscillation circuits were used only in areas where low output power was required.

The present invention was devised in view of the actual state of the prior art as described above, and its purpose is to make it possible to extract medium to high output power at a low cost and with little power loss, and to reduce this output voltage. An object of the present invention is to provide a self-excited converter that can achieve constant voltage with a simple configuration.

The present invention, which can achieve such objects, uses the conventionally used blocking oscillation circuit and output circuit as they are, and provides a separate excitation switching section between them, so that the blocking oscillation circuit functions as a pulse generator. The above object is achieved by having the main switching transistor function as well as the function of a driver for driving the main switching transistor.

That is, the self-commutated converter of this invention has a blocking oscillation circuit including a transformer and a transistor connected in series with the transformer, and an output circuit for rectifying and smoothing an alternating output. A separately excited switching section consisting of a main transformer and a main switching transistor connected in series to the main transformer is provided between the oscillation circuit and the output circuit, and a rectangular switching section excited on the secondary side of the transformer of the blocking oscillation circuit is provided. The main switching transistor of the separately excited switching section is driven by the voltage, and the output of the main transformer of the separately excited switching section is supplied to the output circuit, and the auxiliary winding provided on the main transformer of the separately excited switching section is The output is connected to the base of the transistor of the blocking oscillator circuit through the constant voltage control section.
The gist is that the emitters were connected.

Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 2 is a circuit diagram showing an embodiment of the self-excited converter according to the present invention. As is clear from the figure, this self-commutated converter includes a blocking oscillation circuit 1 comprising a transformer T1 and a transistor Q1 connected in series with the transformer T1, and an output circuit 2 for rectifying and smoothing an alternating output.
In the self-excited converter, a separately excited switching section 4 is provided between the blocking oscillation circuit 1 and the output circuit 2, and includes a main transformer T2 and a main switching transistor Q2 connected in series to the main transformer T2. and drives the main switching transistor Q2 of the separately excited switching section 4 with a rectangular voltage excited on the secondary side of the transformer T1 constituting the blocking oscillation circuit 1,
The output circuit 2 is configured to supply the output of the main transformer T2 to the output circuit 2. The main transformer T2 has
An auxiliary winding n is provided, and its output is connected between the base and emitter of the transistor Q1 of the blocking oscillation circuit 1 via the constant voltage control section 3. Thereby, the pulse width of transistor Q1 of blocking oscillation circuit 1 is controlled in accordance with the output voltage.

Now, the operation of the self-commutated converter configured as described above is as follows. First, in the blocking oscillation circuit 1 as in the conventional case, the transistor Q1 and the transformer T
1 causes blocking oscillation. At this time, a collector current I1 as shown in FIG. 3 flows through the collector of the transistor Q1. The voltage V1 induced on the secondary side of the transformer T1 when the transistor Q1 is conductive causes the main switching transistor Q2 to conduct, and a collector current I2 flows through its collector as shown in FIG. and,
Power is supplied to the load side via the main transformer T2 while the main switching transistor Q2 is conductive. At that time, the constant voltage control section 3 controls the pulse width of the transistor Q1 of the blocking oscillation circuit 1 according to the voltage induced in the auxiliary winding n of the main transformer T2, thereby increasing the output voltage. This results in a constant voltage.

In addition, the main switching transistor Q2 is driven by a rectangular voltage excited on the secondary side of the transformer T1 of the blocking oscillator, and the main switching transistor Q2 is driven by the winding of the transformer T1.
Since a reverse bias V _BE is also applied to the power, power loss during power transmission can be reduced.

As can be seen from the above description, by increasing the capacity of the main transformer T2 and the main switching transistor Q2 of the separately excited switching section 4, a considerably large output capacity (for example, about 150 W or less) can be obtained.

As described above, the present invention is a self-excited converter in which the blocking oscillator circuit is configured to function as both a pulse oscillator and a driver for the main switching transistor. It is possible to increase the output capacity by about five times compared to the previous model, and it is also possible to design such switching regulators with medium and high output power cheaply and easily, and with less power loss. The practical effects are extremely large, such as being able to make the output voltage constant with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional technique, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing operating waveforms of each part thereof. DESCRIPTION OF SYMBOLS 1... Blocking oscillation circuit, 2... Output circuit, 3... Constant voltage control section, 4'... Separately excited switching section, T2... Main transformer, Q2... Main switching transistor.

Claims (1)

[Claims for Utility Model Registration] A self-excited converter comprising a blocking oscillator circuit comprising a transformer and a transistor connected in series with the transformer, and an output circuit for rectifying and smoothing an alternating output; and an output circuit, a separately excited switching section consisting of a main transformer and a main switching transistor connected in series to the main transformer is provided, and a rectangular voltage excited on the secondary side of the transformer of the blocking oscillator circuit is provided. drives the main switching transistor of the separately excited switching section, supplies the output of the main transformer of the separately excited switching section to the output circuit, and further includes an auxiliary winding provided on the main transformer of the separately excited switching section. A self-excited converter in which the output of the line is connected between the base and emitter of the transistor of the blocking oscillation circuit via a constant voltage control section.